Nonlinear heat transfer in Beam Optics Analyzer

Summary form only given. Calabazas Creek Research (CCR) has been developing Beam Optics Analyzer, an adaptive mesh, finite element, charged particle trajectory modeling tool for designing 3D electron devices for the past decade. Several analysis types are already available in Beam Optics Analyzer (BOA) including electrostatics, beam optics, electrostatic PIC, nonlinear magnetostatics, inhomogeneous Helmholtz and linear heat transfer. However, simulating electrodes in the proximity of standard thermionic emitters at high temperatures does require nonlinear heat transfer capability. Toward the goal of making BOA a multiphysics modeling and simulation tool for electron beam devices, we will present the new nonlinear heat transfer capability in BOA. We will discuss the finite element formulation and numerical results with regard to temperature dependent materials and radiative heat transfer coupled with power densities generated from electron beams. We will describe BOA underlying multiphysics technology, which includes the sharing a single CAD model across multiple analysis types, seamless transferring the power density field generated by the electron beam from beam optics to heat transfer, the finite element nonlinear heat transfer formulation, radiation boundary condition and heat exchanges in a radiation cavity. We will present the Monte Carlo method based on the Markov chain, radiation related probability density function and ray tracing techniques to compute radiation exchanges in a cavity. A gridded gun example will be used as a test vehicle to simulate the grid heating due to radiation and electron interception from the emitter. Heat transfer numerical results will be verified against another commercial package Cosmos.